Add configurable Pi Web data directory

src/server/sessiond/config.ts

@@ -1,8 +1,8 @@
-import { homedir } from "node:os";
 import { join } from "node:path";
+import { piWebDataDir } from "../../config.js";
 
 export function sessiondSocketPath(): string {
-  return process.env["PI_WEB_SESSIOND_SOCKET"] ?? join(homedir(), ".pi-web", "sessiond.sock");
+  return process.env["PI_WEB_SESSIOND_SOCKET"] ?? join(piWebDataDir(), "sessiond.sock");
 }
 
 export function sessiondHttpUrl(): string | undefined {